Antenna For An Implantable Medical Device

• US 20120029323A1
• Filed: 07/30/2010
• Published: 02/02/2012
• Est. Priority Date: 07/30/2010
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Zhao, Yanzhu
• Granted Patent: US 9,610,450 B2
• Time in Patent Office: Days
• US Class Current: 600/302
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: A61N 1/37516 Intravascular implants
• CPC Class Codes: A61N 1/37518 Anchoring of the implants, e.g. fixation

Abstract

This disclosure describes antenna structures for use in an implantable medical device. The antenna structure may include an inner portion that is magnetically coupled to an outer portion. In one example, the inner and outer portions comprise conductive loops. In accordance with the techniques of this disclosure, a capacitive sensor is electrically coupled to one of the conductive loops of the antenna of the implantable medical device. As the capacitance of the capacitive sensor changes as a function of the sensed parameter, an impedance of the antenna varies with the output of the capacitive sensor. This variation in impedance of the antenna modulates a carrier signal with the measured parameter. In other words, the measured parameter is modulated onto the carrier signal as a change in amplitude caused by variation in impedance of antenna during radiation/transmission.

Claims

1. An apparatus comprising:

a capacitive sensor having an output that changes as a function of a sensed parameter;

an antenna electrically coupled to the output of the capacitive sensor, wherein a characteristic of the antenna changes as a function of the output of the capacitive sensor; and

a signal generator that generates a carrier signal and provides the carrier signal to the antenna, wherein the changes in the characteristic of the antenna modulates the carrier signal with the sensed parameter.

2. The apparatus of claim 1, wherein the characteristic of the antenna is an impedance of the antenna that changes as a function of the output of the capacitive sensor.

3. The apparatus of claim 2, wherein the changes in the impedance of the antenna change an amplitude of the carrier signal to amplitude modulate the carrier signal with the sensed parameter.

4. The apparatus of claim 1, wherein the antenna includes:

a first portion having a conductive loop electrically coupled to the signal generator; and

a second portion magnetically coupled to the first portion to couple signals between the first portion and the second portion,

wherein the capacitive sensor is electrically connected to one of the first portion or the second portion.

5. The apparatus of claim 1, further comprising a housing that encloses one or more components of the apparatus, wherein the first portion of the antenna comprises a conductive loop located within the housing.

6. The apparatus of claim 5, wherein the second portion of the antenna comprises a conductive loop located outside of the housing.

7. The apparatus of claim 5, wherein the second portion of the antenna comprises a mechanical structure that affixes the apparatus to a target location.

8. The apparatus of claim 7, wherein the mechanical structure comprises a cylindrical stent-like structure that is configured to lodge against a vessel wall.

9. The apparatus of claim 1, wherein the capacitive sensor comprises one of a pressure sensor, a flow sensor and a chemical composition sensor.

10. The apparatus of claim 1, wherein the signal generator generates a continuous wave carrier signal.

11. The apparatus of claim 1, further comprising a processor that controls the signal generator to intermittently generate the carrier signal.

12. The apparatus of claim 1, further comprising a therapy delivery module that delivers a therapy to a patient.

13. A method comprising:

generating a carrier signal;

feeding the carrier signal to an antenna; and

adjusting a characteristic of the antenna as a function of an output of a capacitive sensor to modulate the carrier signal during transmission.

14. The method of claim 13, wherein adjusting the characteristic of the antenna comprises adjusting an impedance of the antenna as a function of the output of the capacitive sensor to modulate the carrier signal during transmission.

15. The method of claim 13, wherein the capacitive sensor comprises a capacitive pressure sensor and adjusting the characteristic of the antenna comprises adjusting an impedance of the antenna as a function of the output of the capacitive sensor to modulate the carrier signal during transmission with pressure measurements.

16. An apparatus comprising:

a capacitive sensor having an output that changes as a function of a sensed parameter;

an antenna having a first portion having a conductive loop within a housing of the apparatus and a second portion outside of the housing of the apparatus and magnetically coupled to the first portion to couple signals between the first portion and the second portion, wherein the antenna is coupled to the output of the capacitive sensor; and

a signal generator electrically coupled to first portion of the antenna to provide a carrier signal to the antenna;

wherein a characteristic of the antenna changes as a function of the output of the capacitive sensor to modulate the carrier signal with the sensed parameter during transmission.

17. The apparatus of claim 16, wherein the characteristic of the antenna is an impedance of the antenna that changes as a function of the output of the capacitive sensor.

18. The apparatus of claim 17, wherein the changes in the impedance of the antenna change an amplitude of the carrier signal to amplitude modulate the carrier signal with the sensed parameter.

19. The apparatus of claim 16, wherein the output of the capacitive sensor is electrically connected to the first portion of the antenna.

20. The apparatus of claim 16, wherein the output of the capacitive sensor is electrically connected to the second portion of the antenna.